An automatic flush toilet, such as an automatic flush urinal stool or basin, is provided with a water discharge apparatus which automatically discharges a predetermined quantity of water to flush the urinal basin after a usage of the urinal basin. Discharging either a predetermined quantity of water or water for a predetermined period of time is controlled by a user or person relieving himself That is, an electric object sensor, such as are comprised of photo-electric elements, is installed in or near the urinal basin to detect the person standing before the urinal basin. When the object sensor detects a disappearance or absence of the person from the urinal basin after having once detected the person relieving himself, the water discharge apparatus is caused to automatically discharge water to flush the urinal basin. In order to reduce electric power consumption for a battery or a source of electric power providing power to the water discharge apparatus, the object sensor is designed and adapted to be actuated timely.
For the purpose of providing a brief background that will enhance an understanding of the present invention, reference is made to FIGS. 1A to 1C showing a practical power supply system of a prior art automatic water discharge apparatus.
Referring to FIGS. 1A to 1C, a photo-electric sensor circuit, having a light emitting element and a light receiving element, is intermittently supplied with a predetermined voltage of electric power PW on a controlled cycle, for example usually one (1) sec. as is shown in FIG. 1C. The light emitting element, such as an infrared light emitting diode, is energized to emit infrared light pulse PL on the same controlled cycle as shown in FIG. 1A. The light receiving element detects the infrared light pulse reflected by a person standing before the urinal basin to provide an output signal pulse PR as long as the person remains before the urinal basin as shown in FIG. 1B. The signal pulse PR disappears from the light receiving element immediately after the person moves away from the urinal basin. The disappearance or absence of signal pulse causes a water discharge valve to allow water to be discharged and flush the urinal basin.
Whereas the prior art automatic water discharge apparatus has been constituted in an attempt to lower the consumption of electric power in its own way, nevertheless, since the photo-electric sensor circuit itself consumes electric power to a considerable extent, it is impossible to reduce sufficiently the consumption of electric power. Thus, the lifetime of a source of electric power is unnecessarily shortened, or power is unnecessarily consumed.